Saturday, December 31, 2011

This reproduction of a roughly 188 meter wide segment (between lines 18602 and 19053) of LROC Narrow Angle Camera (NAC) observation M168000580R may not be the best view of the Apollo 17 lunar module descent stage or the rover tracks and foot prints left behind by Cernan & Schmitt in 1972, still it was collected from an altitude of only 22.41 kilometers on August 14, 2011; LRO orbit 9892, official resolution 0.41 meters per pixel with an incidence angle of 45.17° [NASA/GSFC/Arizona State University].

Joel RaupeLunar PioneerSince the latest release of Lunar Reconnaissance Orbiter Camera (LROC) images on December 15 we've been able to get a better idea of what flight directors were up to last August. As advertised, the record-breaking spacecraft's roughly 50 kilometer high circular polar orbit was briefly lowered to allow a narrow window for very low altitude photography. The lowest perigee (or perilune) appears to have been engineered into orbits 9838 through 9973, between August 10 and August 21, 2011. At least that's the period where LRO Narrow Angle Camera (NAC) frames from last summer are available at resolutions higher than 40 centimeters per pixel.

The area covered, moving westward with the Moon's easterly rotation under the LRO orbit, begin near the nearside's east limb at the 85th meridian traveling short of the 60th meridian west (near 310° east). That period in LRO's August close-up maneuver featured perilunes as low as 22 kilometers over the nearside equator with apogee back up near the Nominal and Science Mission altitude higher than 40 kilometers while over the Moon's farside. Put another way, the very highest resolution LROC NAC frames were captured last August between Mare Marginis west to Aristarchus and the Marius Hills.

Our continued, now more extensive tour, of the LROC August low-altitude close-ups has uncovered many extensive fields of boulders and their trails. The largest boulder seen above on the floor of the Vera (26.32°N, 316.28°E) rille formation, directly adjacent to the Prinz ghost crater and head of a long and deep sinuous rille in Oceanus Procellarum, is roughly 22 by 22 meters in size. Many of these August perilune NAC observations appear fore-shortened in this raw first look. A description of the full-width NAC frame which included the detail above is reproduced below [NASA/GSFC/Arizona State University].

Vera-Prinz. The full width of LROC NAC observation M168488930L, orbit 9964, August 20, 2011; 0.41 meters per pixel with an illumination incidence angle of 43.82° from 26.43 kilometers. The wider image does not provide the context of a Wide Angle Camera image but at least it shows where the boulders further above originated. Is "Vera" is not a crater but a caldera, the "cobra head" of a long and winding rille. The whole scene rests high above the Procellarum basin floor, on the still exposed northeastern ejecta blanket of the almost completely buried ghost crater Prinz. Still, Vera is a deep formation. The lowest elevation inside Vera above is about 550 meters below the surrounding terrain (which only looks flat) [NASA/GSFC/Arizona State University].

The primary purpose of the low altitude maneuvers last August was to allow a last, very close look at three of the six Apollo landing sites, but LROC's targeting team took advantage of the 11 day window to gather hundreds of observations. In addition, the period allowing for greater than 0.4 meter per pixel NAC resolutions was bracketed by a slow, probably energy conserving re-circularizing of the LRO orbit back to within 50 km. There are far more observations among those images between June 15 and September 14 released in December with resolutions higher than the mission average of half a meter per pixel.

There will undoubtedly be thousands more NAC observations captured through December (scheduled for release in mid-March). Though LRO will be placed at an extended mission altitude of greater than 100 km in January it's likely more than half of the Moon's surface will soon be mapped at high resolution, a very successful legacy indeed.

Not every feature on the lunar surface is billions of years old. On edge of the floor of the crater Milichius (9.86°N,329.75°E), seen above, a six meter boulder clearly rolled down the steep wall and came to rest before one of several subsequent dry flows covered the end of its trail, without moving or covering the boulder. The full width of the frame is detailed immediately below [NASA/GSFC/Arizona State University].

As context for the previous full resolution field of view (white rectangle), the full width of LROC NAC frame M168401046L, orbit 9951, August 19, 2011; resolution 0.395 meters per pixel with an illumination incidence angle of 37.62° from 23.08 kilometers. A 64 meter per pixel Wide Angle Camera LROC QuickMap mosaic of the vicinity is available HERE [NASA/GSFC/Arizona State University].

A full resolution frame from a very high resolution LROC NAC observation of a cross-section of landmark nearside crater Bessel (21.73°N, 17.92°E), prominent in the southeastern Mare Serenitatis. This dry flow is composed of material shed from the crater's southwestern wall that did not (or hasn't yet) reached the crater floor. The full width of the NAC frame is reproduced for context in the next image [NASA/GSFC/Arizona State University].

A full width view of LROC NAC frame M168088745L, a breathtaking north-south cross-section of the crater Bessel, August 15, 2011; orbit 9905, resolution 0.395 meters per pixel with an illumination incidence angle of 45.41° from 23.07 kilometers. In this slightly foreshortened view the most prominent feature is the 1325 meter plunge down the southwestern wall of Bessel, from rim to the wall's contact zone with the crater floor [NASA/GSFC/Arizona State University].

China issued a new "white paper" today describing the achievements of its space program over the past 5 years and outlining its plans for the next 5 years. China issued such white papers in 2000 and 2006, and the 2011 version offers little that is new.

According to the English-language version published on Xinhua's website, China has relatively modest plans for its space program, most of which were previously known. No ground-breaking plans were revealed.

"In the next five years, China will strengthen its basic capacities of the space industry, accelerate research on leading-edge technology, and continue to implement important space scientific and technological projects, including human spaceflight, lunar exploration, high-resolution Earth observation system, satellite navigation and positioning system, new-generation launch vehicles, and other priority projects in key fields. China will develop a comprehensive plan for construction of space infrastructure, promote its satellites and satellite applications industry, further conduct space science research, and push forward the comprehensive, coordinated and sustainable development of China's space industry."

As China has indicated in the past, it is developing at least three new launch vehicles for various purposes. A Delta-4 class launch vehicle, Long March 5, is expected to begin operations from a new launch site on Hainan Island in 2014. Designed to place 25 tons into low Earth orbit or 14 tons into geostationary orbit, it will be the largest of China's space launch vehicles. China also is developing a new small launch vehicle, Long March 6, and a new mid-sized rocket, Long March 7, both of which are mentioned in the white paper. No plans for a heavy-lift launch vehicle were announced today, however. Instead the white paper says only that China will "conduct special demonstrations and pre-research on key technologies for heavy-lift launch vehicles."

Assertions by Chinese "experts" quoted in the Chinese media over the
past several years that China was planning to send taikonauts to the
Moon in this decade appealed to those who wanted to catalyze another
"Moon race," but could not be traced back to official government
policy. Today's document, which presumably represents official policy,
says only that China will conduct studies "on the preliminary plan for a
human lunar landing."

Wednesday, December 28, 2011

The long 2.5 million mile tour to the Moon allowed the spin up of mission-sensitive equipment. GRAIL A and B will arrive in lunar orbit 25 hours apart following their more-than three month flight. The science mission will commence as after an 11 hour series of maneuvers bring the vehicles down to their 50 km high circular polar orbit [JPL].

Beginning with New Year celebrations this coming weekend the United States will start 2012 with a total of five unmanned spacecraft in orbit around the Moon simultaneously.

Following a low energy trajectory allowing more than three months flying time the twin lunar Gravity Recovery and Interior Laboratory (GRAIL A and GRAIL B) will be inserted into lunar orbit New Years Eve and New Years Day, respectively. There they will join the ARTEMIS P1 and P2 probes, two salvaged vehicles of the now-completed five vehicle THEMIS fleet subsequently redeployed to the Moon by way of L1 and L2, and the Lunar Reconnaissance Orbiter (LRO) that has been in lunar orbit since June 2009.

Maria Zuber of MIT, principal investigator for the GRAIL mission, joined David Lehman, project manager at NASA's Jet Propulsion Laboratory (JPL) for an audio news conference Thursday afternoon, December 28.

The Gravity Recovery And Interior Laboratory (GRAIL) spacecraft are intended to map the lunar gravitational field with unprecedented accuracy.

GRAIL-A and GRAIL-B lifted off from Cape Canaveral on September 10. GRAIL-A will arrive in lunar orbit at 2100 UT) New Years Eve and GRAIL-B will arrive New Years Day at 2200 UT.

MoonKAM field of view. Piggy-backing on the small Lockheed Martin-built probes, four cameras in total will be operated by elementary school students signed up through the MoonKAM website [Zuber/MIT].

The science payload on-board each spacecraft is the Lunar Gravity Ranging System, which will measure changes in the distance between the two spacecraft down to a few microns - about the diameter of a red blood cell.

The GRAILs also carry cameras for the MoonKAM project, an educational outreach effort which will allow students and schoolchildren to download lunar imagery directly. The results of a contest to formally name both GRAIL A and B is scheduled to be announced following orbital insertion.

"The Moon is the nearest pristine airless body with a preserved surface intact from the time of the Solar System's formation," Zuber said. "We actually now know more about Mars than our closest neighbor."

"We don't yet know fully why there is such a difference between the near and far side of the Moon, and the we think the answer lies within the Moon. GRAIL should complete a gravity map of the Moon 100 times as accurate as we have today."

As both spacecraft stay in line of site through June, approximately 50 kilometers above the surface in polar orbit differences in their distance will be measured to within a few microns, allowing the anisotropic nature of the Moon's mass to measured with unprecedented accuracy.

In addition the probes will carry four cameras between them, admittedly with no true scientific value, that will be operated by students signed up through the MoonKAM project under the direction of former astronaut Dr. Sally Ride.

Following the 84 day nominal mission there is a possibility of an extended mission through December 2012.

Since the 8th 'tri-monthly' Data Release by teams flying instruments on-board LRO on December 15 we've been rushing to sample the latest set of LROC Narrow Angle Camera (NAC) footprints to discover what's new.

After downloading the newly-updated NAC and WAC footprint KML's for viewing with the Google Earth program (through the Planetary Data System (PDS) the first temptation is to try to take it all in. But that's like examining every square nanometer of a basketball with a microscope. So we tried, once again, to begin instead by taking note of new NAC observations of our ever-growing list of favorite targets.

And yet, this latest release was more highly anticipated than any since the Commissioning became the Nominal LR mission in late 2009. Before being redeployed to a more fuel efficient higher orbit in January, last August flight directors reduced the spacecraft's orbital perilune to within 25 kilometers for a brief time. This made possible an even closer examination of three of the six Apollo landing sites, the subject of a NASA news conference in September.

What wasn't generally discussed at the time, however, was what else might have been photographed at 40 centimeters per pixel resolution and greater last August.

Most of the full width of LROC Narrow Angle Camera (NAC) observation M168570575R, orbit 9976, August 21, 2011; incidence angle 37.14° with an original resolution of 0.3994 meter per pixel from 23.98 kilometers. The white rectangle is the smaller field of view shown at the original resolution in the image immediately below. At this low altitude, where LRO was flown for only a brief time last August, it's necessary to step back quite a long way to appreciate the context, in this case a north-south 1000 meter-wide cross-section of the unofficially named "Sinuous Rille A" feature in the Marius Hills region of Oceanus Procellarum [NASA/GSFC/Arizona State University].

The boulder-shedding southern edge of "Sinuous Rille A" as viewed from only 24 kilometers above on August 21, 2011. The original layering of the the surrounding greater Procellarum basin as excavated by more "recent" flows from the Marius Domes is clearly exposed. The smallest features distinguishable are only 40 centimeters in size. The first of the "pit craters" discovered on the Moon here by Japan's Kaguya orbiter team in 2009 is located elsewhere on the floor of this rille. (Field of view only 230 meters) [NASA/GSFC/Arizona State University].

We've been pouring over those images, many of which can be seen using LROC web-based tools, since December 15. A first look seemed to show a rather haphazard, seemingly thin set of targets, taking advantage of a daylight perigee over the equator, in mid-August, with a few exceptions, like the Ina caldera, which stood out enough for us to have taken note of it in a post last week. Over Christmas weekend, as we began collecting notes about what stands out in these low altitude NAC frames from August, LROC principal investigator Mark Robinson posted "Aristarchus Spectacular," featuring a breathtaking mosaic of that landmark nearside crater's bright interior from late in the low altitude orbital maneuver. (We hastily added a few snips to our mirror post that we had already collected showing the same area in even higher resolution taken from an August close-up).

To appreciate the volume of data in dire need of crowd sourcing the basics are worth repeating: According to the December 22 announcement,
by LROC investigator Ernest Bowman-Cisneros, "(t)he 8th LROC Planetary
Data System (PDS) release includes images acquired between 16 Jun 2011
and 15 (Sept.) 2011" including "83,010 EDR images totaling 8.5 Tbytes
and 83,010 CDR images totaling 17 Tbytes... To date, the LROC team has
released a total of 586,217 images (EDR) totaling 64.7 Tbytes. The
complete LROC PDS archive can be accessed via the URL http://lroc.sese.asu.edu/data/."

Context: Color LROC WAC Digital Terrain Model (DTM) 64, showing the location of a massif pictured below, just outside the central ring of mountains surrounding the deep interior basin of Mare Orientale. The area was imaged at unusually low altitude by both NAC and WAC LROC cameras last August, around the time of the now-seasoned orbiter's unprecedented 10,000th orbit around the Moon [NASA/GSFC/Arizona State University].

The LROC Wide Angle Camera
(WAC) was along for the ride last August, when LRO's orbit was
briefly lowered to within a 25 kilometer perigee. On August
21 LROC swept up this 4000 meter-high massif just beyond the northeastern interior of Mare Orientale (9.5°S, 91.64°W), seen here
in a mosaic at 604 nm from three sequential passes
averaging 33.4 kilometers above. The resolution averages around 48 meters per pixel [NASA/GSFC/Arizona State University].

A bit of cutting and pasting allowed the filling in of this LROC NAC footprint (M168808506L and R) in three dimensions. The area within the white square is detailed below [NASA/GSFC/Arizona State University].

The very steep slope of the unnamed massif blown up to 2 meter per pixel resolution does little justice to the original. LROC NAC M168808506R, orbit 10011, August 20, 2011; illumination incidence angle 32.96° with a raw resolution of 44.2 centimeters per pixel from 33.2 kilometers [NASA/GSFC/Arizona State University].

At full resolution, the boulder and it's interrupted trail down the south face of the massif show signs of space weathering. It's by no means the most spectacular feature in the August lower altitude NAC frames [NASA/GSFC/Arizona State University].

It's a lot of data to sort through, yet again breaking LRO's own already well-established record for having returned more data from deep space than all of mankind's probes sent beyond low Earth orbit put together.

There are boulder trails, to be sure, and though it may be only our imagination but there seems to be more than a random share of small, bright impact craters in the set. The best candidate for the impact crater formed by the Apollo 15 lunar module ascent stage, for example, was swept up yet again. As we begin to sort out our notes in greater order we look forward to posting better examples from this unique set. Like every other lunatic following LRO's steady progress we look forward to seeing and reading what Robinson's LROC team at Arizona State has uncovered in these frame also.

Now that's an interesting boulder trail! From only 23 kilometers overhead, a chunk of ring-bound upthrust the size of a passenger trail locomotive has rolled down and pitted this shallow incline near the dead center of Mare Serenitatis. The August "close-up window" enjoyed briefly by LROC's NAC system seems to have had its advantages centered on the nearside longitudes and just beyond either limb. LROC NAC M168081909R, LRO orbit 9904, August 15, 2011; incidence angle 46.74° with a resolution of 39 cm per pixel from 23.06 kilometers [NASA/GSFC/Arizona State University].

A long established year-end tradition – for good or ill – is a review and analysis of the preceding twelve months. Who am I to fight this trend? Being that I am a “the glass is not only half-empty, but chipped and cracked down the middle” space policy town crier, be fairly warned as I conclude this year’s blogging with a look back at 2011.

The retirement of the Space Shuttle this past year vindicated T.S. Elliot’s pronouncement about the nature of the end of the world. The U.S. workhorses that ferried Station pieces and crew to low Earth orbit await their museum berths. The most heated emotions and debate surrounding this event dealt with the agency’s selection of the final resting places for the working U.S. space access machines. To the outrage of many, space-oriented places like Houston and Huntsville were cold-shouldered in favor of show business-oriented Los Angeles and New York City. In the heat of this controversy (so dire that members of Congress from space-economy communities rose from their slumber to pen op-eds mirroring constituent alarm), few noticed or understood that without a replacement, the country’s capability for humans to access space had been discarded. As 2011 closes out, construction and assembly of the International Space Station is complete – it is a unique Earth-orbiting platform for ongoing scientific research, accessible for the price of a ride on a Russian Soyuz spacecraft.

This past year was heralded as the opening chapter for a new approach to human spaceflight – the American civil space program was to advance more economically through the use of commercial launch services to LEO. We’re waiting and watching, with more than a little trepidation, as millions of taxpayer dollars are doled out to “New Space” companies branded “commercial.” Recent history shows taxpayer-funded, new-technology enterprises have failed spectacularly. It’s troubling that simultaneously, these space access ventures are making similar claims of soon-to-be superior, cheap alternatives toward solving a pressing national problem.

After being kicked long and hard by the Congress, NASA finally decided that they should probably go ahead and build a new launch vehicle. Despite some initial foot-dragging (and the conspicuously ignored presence of an obvious and inexpensive alternative), the agency buckled down and produced a design for a new heavy lift launch vehicle, one that looks remarkably similar to the now-discarded Ares system. With continued work on the new Multi-Purpose Crew Vehicle, looking remarkably similar to the now-discarded Orion spacecraft, we soon will be ready for new and exciting missions to untrod landscapes in space – perhaps a large rock –in a decade. Maybe. Perhaps even for less than its estimated $100 billion cost.

Robotic science missions, the so-called “crown jewels” of the space program, had their own share of difficulties this year. The Goddard-run James Webb Space Telescope, the second-generation successor to the highly successful Hubble Space Telescope, is coming in late with a price tag of more than $8.7 billion and counting. Its continued cost growth threatens all NASA space science programs. JPL’s own giga-project, the $2.5 billion Mars Science Laboratory, was successfully launched and will encounter the planet in about six months, hopefully at very low velocity. Less costly robotic missions to a variety of destinations continue to return copious amounts of data; whether there will be money to reduce and analyze it all remains uncertain.

To their own and the nation’s detriment, NASA is trapped by one model when thinking about space. Missing is the notion of permanence and expansion into space. A variety of “anyplace-but-the-Moon” destinations for human spaceflight have been mooted and studied in the past year, including near-Earth asteroids, L-points, the tiny, asteroid-like moons of Mars, lunar orbit, and even a human Venus flyby. All of these imagined missions require knowledge, hardware and technologies that we do not now possess. All expose human crews to substantial risk through long-term exposure to radiation and microgravity. None create permanence of human presence or extension of capability in space. And all travel to destinations offering little scientific and exploratory benefit or variety; their main attraction seems to be the yet-to-be-explained agency imperative to cross them off some “been there” check-list.

Several plans to develop cislunar space through an incremental, step-wise approach have been advanced. The goal in each is not a flags-and-footprints type of space extravaganza, but the steady expansion of capabilities and reach beyond low Earth orbit. Such a modus operandi is possible through the development and use of lunar resources —specifically the water ice found in quantity at both poles of the Moon. In stark contrast to the Apollo template (and regardless of budgetary ups and downs), constant, steady and measurable progress can be realized through the creation of this “transcontinental railroad” in cislunar space.

I note with sadness, the passing of some great space visionaries this year. John Marburger, former Presidential Science Advisor, was one of the few who truly understood the meaning and purpose of the Vision for Space Exploration. Lunar and planetary scientists Baruch Blumberg, Bill Muehlberger, Mike Drake, Paul Lowman, Nick Short, Chuck Sonett, and my academic advisor and friend Ron Greeley passed away this year. Theirs were voices of knowledge and experience and they will be missed.

The year 2011 was an annus horribilis for the national space program. Here’s to the forthcoming year and hopes for a return of sanity to space policy.

Monday, December 26, 2011

West wall of Aristarchus crater seen obliquely by the LROC Narrow Angle Cameras from an altitude of only 26 kilometers. Scene is about 12 kilometers wide at the base, NAC observation M175569775, LRO orbit 11008, November 10, 2011. View the full resolution west wall panoramic image HERE [NASA/GSFC/Arizona State University].

The Aristarchus plateau is one of the most geologically diverse places on the Moon: a mysterious raised flat plateau, a giant rille carved by enormous outpourings of lava, fields of explosive volcanic ash, and all surrounded by massive flood basalts. A relatively recent asteroid (or comet) slammed into this geologic wonderland, blowing a giant hole in the ground revealing a cross section of over 3000 meters (9800 ft) of geology. No wonder planners for the Apollo missions put this plateau high on its list of targets for human exploration. This amazing image was acquired on 10 November 2011 as LRO passed north-to-south about 70 km east of the crater's center while it was slewed 70° to the west. The spacecraft was only 26 km (16.2 miles) above the surface; about two times lower than normal. For a sense of scale, that altitude is only a little over twice as high as a commercial jets fly above the Earth!

Full panoramic view of the west wall of Aristarchus crater revealing impact melt deposits, exposures of high reflectance, anorthosite, streamers of pyroclastic ash and blocks up to 100 meters in size. Full width of panorama is about 25 km, M175569775 [NASA/GSFC/Arizona State University].

Aristarchus crater is located on the southeast edge of the Aristarchus Plateau. This gaping crater is 40 km wide and 3.5 km deep. The ledges forming the wall of the crater, which look a lot like those of a strip mine, are actually blocks of pre-impact crustal and surficial rocks that slumped into the crater during the late stages of its formation. The impact that formed this crater occurred on a mare-highland boundary and thus excavates a variety of rock types.

The LROC NAC footprint for observation M168516102, from which the following six oblique views were cropped, all of them from the right frame and spotlighting areas within the northwest rim of bright Aristarchus. The view above simulates an oblique view of the area, most if which is also found within the LROC Featured Image released December 25, 2011, from a point well south of Aristarchus Plateau 25 kilometers in altitude [NASA/GSFC/Arizona State University].

Dawn View of Aristarchus: Sunrise lighting enhances surface texture on Aristarchus crater (40 km diameter). Northwest (upper left) of the crater is the mysterious Aristarchus plateau, to the east, southeast, and south lies the edge of the vast mare Oceanus Procellarum. Small white arrows indicate approximate corners of the NAC panorama, In the full size LROC context image, a vertical line on the right shows the LRO orbit ground track when the Featured Image NAC panorama was acquired. (LROC WAC mosaic) [NASA/GSFC/Arizona State University].

The ledges forming the crater wall, which have a scalloped appearance, are sagging blocks of the pre-impact lunar crust. Bright and dark materials are exposed in patches along the walls. Dark streaks of impact melt and debris cover some of these materials (dark region from top-to-bottom just left of center). Pyroclastic beads (volcanic glasses formed during fire-fountain style eruptions similar to those of Stromboli or the Hawaiian Islands) that blanket the area around the crater have slid down parts of the walls in dark streaks and clumps (visible as small dark streamers across the top of the crater in the center of the panorama). These pyroclastic deposits represent one of the largest, most accessible exploration-enabling resource deposits on the nearside of the Moon. Despite the blanket of dark glassy materials, Aristarchus crater is still one of the most highly reflective areas on the Moon. Much of this high reflectance is due to the excavation of rocks from deep in the crust. These deep rocks may be anorthositic like the highlands, or they may be a more silicic rock like granite (or both). Although granites have been found in Apollo rock samples, the formation of granite on the Moon is not well understood at this time - another reason why we need to get samples from this region!

Early afternoon Aristarchus: Early afternoon WAC mosaic of Aristarchus crater to compare with the sunrise mosaic above. Again, small white arrows indicate the approximate corners of the Featured Image NAC panorama, and in the original context image a vertical line on the right (beyond the field of view of this crop from the original) shows LRO orbit ground track [NASA/GSFC/Arizona State University].

Look closely at the early afternoon lighting WAC mosaic; you can clearly see that some of the Aristarchus ejecta has high reflectance, and some has low reflectance. This contrast reflects the compositional difference between the target rock. The northwest portion was mostly basalt and ash, while the south-southeast was predominantly crustal rocks (anorthosite and/or granite).

The floor of Aristarchus crater provides explorers a unique opportunity to study a wide variety of lunar rocks and geologic processes, possibly including how lunar granite forms. Diverse materials such as dark, multilayered mare basalts in the walls, bright crustal rocks in the central peak, impact melt, and even regional pyroclastic materials blanketing the crater are brought to the floor and accumulated through mass wasting, creating a bountiful trove of
geologic materials.

Friday, December 23, 2011

This fresh crater in the north-central Oceanus Procellarum basin has a
"bench" along its crater wall, and boulders are strewn among its ejecta
blanket. What does this crater tell us about the local geology? LROC
Narrow Anle Camera (NAC) observation M160363812RE,
orbit 8767, May 18, 2011, incidence angle after local sunrisei was
57.87° from the southeast; image field of view is 500 meters with an
original resolution of 47.8 centimeters per pixel from 40 kilometers.
View the original 1000 x 1000 pixel LROC Featured Image HERE [NASA/GSFC/Arizona State University].

Bench craters form in terrains where two layers exist with substantially different strengths. On the Moon this is normally interpreted as a loose regolith covering a more cohesive bedrock. Because less energy is needed to penetrate the regolith than the bedrock, the crater develops a bench at the boundary between regolith and bedrock. Using this interpretation, we can estimate the depth of regolith. In the case of today's Featured Image we can interpret that a thin layer of regolith is covering the layered mare deposits within Oceanus Procellarum.

But how meaningful is a regolith thickness estimate from one crater? Regolith is created as small impacts churn up the top layer of a surface. As more and larger impacts occur, the regolith grows in thickness. However, impact events are not evenly distributed, and regolith thicknesses can vary in a small area. One way to more accurately determine the regolith thickness is to then document all the bench craters in a given area. From this data an isopach map can be made, showing the thickness of the regolith for that area!

Friday, December 16, 2011

Go the the LROC QuickMap "and grow wise." Select the NAC footprints overlay from the left side of the QucikMap interface and study their individual patterns. Logically, the larger the footprint the higher the vantage point. If you look very closely, in a few places, more in one hemisphere than the other, there are the most narrow and smallest of NAC footprints. Those are the very closest of close-ups of the lunar surface, captured during a brief low-perigee phase in the LRO mission last August, part of the 8th release of LROC imagery to the Planetary Data System, December 15 [NASA/GSFC/Arizona State University].

It's a storied challenge for the most talented and best equipped amateur telescopes. The much studied nearside 'caldera' "Ina" is seen above prior to local sunset on January 6, 2010; a roughly 46 kilometer-wide LROC Wide Angle
Camera (WAC) color (689 nm) field of view stitched from sessions in sequential
orbits. (Down slope from the feature, to the east by southeast, younger
surface material may be a hint of pyroclastic flow). A window of very low pass orbits LRO took over the lunar surface last August allowed LROC team members to take a few extreme close-ups, among those released December 15. One of these is detailed below [NASA/GSFC/Arizona
State University].

Joel RaupeLunar Pioneer

LRO data collected June 14 - September 15, 2011 is now available through the Planetary Data System (LRO Node), the 8th such consecutive release. Details on its size and scope should be posted by the Lunar Reconnaissance Orbiter science teams shortly.

Among these data are the latest available images collected in those 90 days by the Lunar Reconnaissance Orbiter Camera (LROC) team at Arizona State University. The LROC QuickMap and other web-based indexes have been updated to include this newest set, though the LROC News System has been unusually quite, so far, announcing their availability.

From February 2010 (LRO orbit 2791) "Ina" (18.65°N, 5.3°E) is seen here in a montage of 10000 lines taken from both the left and the right frames of Narrow Angle Camera (NAC) observation M119815570. Ina is "an extremely young and unusual 3 by 2 km
depression that may represent a gas eruption site on the Moon" [NASA/GSFC/Arizona State University]

Scientists are busy people. The image some of us have of Einstein, Bohr and Schrödinger lounging around a smoking salon or discussing the impossible melding of Quantum Mechanics and Special Relativity in a random walk in the park, relates with modern science as well as John Wayne's earliest movies match up with the real Wild West.

And it's an unusual set of images. Last August, for a brief period, LRO was brought closer to the lunar surface, to perilune heights sometimes below 24 kilometers. As discussed at the time the spacecraft afterwards returned to it's mission profile, low-eccentricity polar orbit of around 50 kilometers, but next month, to save fuel for its extended mission, the orbiter will be raised to the longer-term stability of a 100 kilometer polar orbit. As such, we're not likely to see LROC Narrow Angle Camera close-ups of the lunar surface as detailed as some collected in August until End of Mission.

It's a little misleading to post this latest, somewhat oblique raw LROC NAC August close-up of Ina. It's from the left frame of M168170208, and with a somewhat oblique resolution of 40 centimeters per pixel, from 24.19 km in altitude, it does not seem much more detailed than what the eye first sees looking at the same field taken from the left side of M119815570, from nearly twice the altitude. Other than for dramatic affect, the only reason to add the image above to the sequence is to provide some context.

After spending a few hours looking through a sample of the LROC August close-ups, I'm reminded of something Charles Wood (LPOD) wrote after the first releases of LROC NAC images in 2009. He looked forward to the release and assembly of the mission's Wide Angle Camera imagery, he said. As breathtaking and beautiful as the NAC images were, they seemed almost too difficult to interpret without context. The science of the mission was not readily available to the unassisted human eye. The contact between one's nose and face is easy to see, but an inch away it can all seem like the same skin.

The full 40 centimeter per pixel close-up of the southern "contact" between Ina and "that which is not Ina" from LROC NAC M169170208L, orbit 9917, August 16, 2011. Incidence angle 43.28° The field of view above is around 230 meters across.

There may not be a lot of eye-candy in the LROC August 2011 close-ups, but those who are patient and observant, those who understand at least some of the context of what they are seeing in these images, will undoubtedly make new discoveries.

Wednesday, December 14, 2011

Grooves carved out by ejecta during the Herigonius K impact event (to the immediate southeast)
provide channels for impact melt to flow outward. Small cracks can be
seen on the impact melt surface, possibly from contraction as the impact
melt cooled. LROC Narrow Angle Camera (NAC) M135426635LE,
orbit 5091, August 2, 2010; incidence angle 57.53° Image sample field
of view is 500 meters, resolution 48 cm per pixel from 41.26 kilometers.
View the original full size LROC Featured Image HERE [NASA/GSFC/Arizona State University].

Impact melt is a common feature inside fresh craters on the Moon. Less common, but no less spectacular, are impact melt flows that were emplaced just outside their parent craters and flowed downslope. Because impact melt is fluid when it lands, it flows down the flanks of the crater until it reaches an impasse and pools in low lying areas. The impact melt flow in today's Featured Image has done exactly this. The surface that the impact melt flowed down appears grooved. These grooves were probably carved out by ejecta when the impact occurred. Soon after, the impact melt was deposited and was able to follow the grooves downslope until meeting an obstacle.

Full approximate 2.1 kilometer width field of view centered on the impact melt flow, explosively channeled to the northeast from the impact event that formed Herigonius K. The crater's rim is visible in the southeast, lower left corner.[NASA/GSFC/Arizona State University].

LROC
Wide Angle Camera (WAC) Global 100 meter mosaic textured over the LOLA
digital elevation model (v.2) available within the ILIADS GUI (LMMP) - a
simulated oblique view from a point about 15 kilometers over Oceanus
Procellarum, north of Herigonius K. A context image for the history of
melt flow already evident nearby in the form of the long sinuous rille
Rimae Herigonius. The latter channel winds around from the north
(bottom) and then far to the southwest, nearly beyond Gassendi (high-rim
crater near the horizon at upper right) and into distant Mare Humorum.
The location of the impact melt flow is shown by the small yellow arrow
[NASA/LMMP].

December 14, 1972. Geologist Dr. Harrison "Jack" Schmitt, the only professional scientist to visit another planet, swaps poses with Apollo 17 commander Capt. Gene Cernan following completion of their third and final EVA, exploring Taurus Littrow. It was the last Apollo moonwalk and the end of a breathtakingly successful sixth manned expedition to the lunar surface. When humans may resume this sorely needed activity is no more certain now than it was when, with little ceremony, Cernan climbed back into Challenger to prepare for lift-off. They were ahead of their time, they made it look easy, and the success of such a program at such a time arose from determined political will that was a product of events both wonderful and tragic. But regardless how history coldly credits events, unique and common, for Apollo, today we are without excuse. There is no retreat from tomorrow, and it's long past time to resume this inevitable enterprise, if only for the simple reason that our understanding of our Earth will never be complete without a proper exploration of Earth's Moon, our "deep water access" to the truly endless sea beyond [NASA/ASJ/].

One of the last major milestones in the history of terrestrial exploration was achieved one hundred years ago today – the attainment of the South Pole by Roald Amundsen and his team on December 14, 1911. His rival, Robert Falcon Scott and crew, were still more than a month away from the pole and (although denying they were in a race) destined for heartbreaking disappointment when they arrived to find the Norwegian flag flapping in the howling Antarctic wind.

The Amundsen-Scott polar drama time stamps a major shift in our thinking about the meaning of exploration. This shift in our perception of what it means to explore holds ramifications to today’s debates on space policy. Traditionally, exploration is a very personal activity. It involves someone’s decision to see what lies over the next hill. This act is exploration in its purest sense; it dates from the Stone Age and is principally responsible for humanity’s reach into all corners of the Earth. This exploration is undirected and random –motivated by the human desire to scratch that unrelenting itch of curiosity. You finance and outfit yourself and go, while adhering to the maxim, “It is easier to ask for forgiveness than to get permission.”

As society grew and evolved, a different type of exploration emerged. For difficult or expensive journeys to far corners of the globe, people pooled their knowledge and resources to collectively explore the unknown by creating government-sponsored projects. Until modern times, such exploration was considered to include not only discovery and initial characterization, but also utilization, exploitation and eventually colonization – all with an eye toward wealth-creation. By the end of the 19th Century, the regions of the world unclaimed by western powers were all but gone, gobbled up in a frenzy of imperial land-grabs by industrially developed nations. All that was left were the seas (whose freedom of access for all nations was guaranteed by the British Royal Navy) and the North and South Poles.

The shift of attention to the poles coincided with the rise of science and with it, a significant change in the “exploration” ethic. It was actually thought at one point in the late 19th Century that all nature had been finally and thoroughly explained. After numerous failed attempts to find a Northwest Passage to the Pacific north of Canada (economic motivation), expeditions to the polar regions began to focus on scientific observations and measurements (knowledge gathering). This shift in emphasis also coincided with a global rise of nationalist conscience, the idea that some nations were destined to discover and conquer remote parts of the Earth. Given the global extent of the British Empire at that time, the English were particularly susceptible to this idea.

These various motivations were threaded together in the early 20th Century as science joined with nationalistic chest-thumping to create government-sponsored scientific expeditions to remote locales. Important and difficult expeditions requiring teamwork and pooled resources became national exploration efforts. Science became a fig leaf rationale for realpolitik global power projection. There was still the occasional “because it’s there” type of expedition to some remote mountain or plateau but most often it was privately financed.

And so we come to the Space Age, which in basic terms has followed the knowledge-gathering template of polar exploration. A new movement for national power projection in space has yet to fully emerge. National security may be the only motivator of sufficient political power to launch an earnest, national drive into space. Traditionally the military conducts exploration in peacetime. In the late 18th Century, Royal Navy Captain James Cook conducted three expeditions to the Pacific – not for pure science but rather for applied science – to improve navigation for commerce and other purposes.

Perhaps this link to applied science may guide us toward a new understanding of the term “exploration,” or rather, to recover an old meaning that has been lost. The idea of exploration leading to exploitation (currently tossed aside in the modern equation of exploration and science) could serve as the “new” guiding principle for modern spaceflight. By making space the singular preserve of science and politics, both are ill served, much to the determent of humanity. For now, we remain wedded to the template of launch, use, and discard – a modus suitable to an occasional, expensive and limited presence in space but one wholly inappropriate for undertaking the creation of a modern, permanent space faring infrastructure. Instead, beginning with the creation of a reusable, extensible cislunar space faring system, we should learn how to use space for national interests by using the Moon and its resources. This will require a long-term research and development project geared to acquiring the understanding and ability to gather and use the resources available to us in space in order to routinely access, explore and exploit cislunar space and the frontier beyond.

This model of a national space program fits the classic understanding of exploration – we go into space as a society and what we do there must have societal value. Because cislunar space has critical economic and national security value, we need to create a system that can routinely accesses that region of space with robots and people. Hence, I advocate resource production bases on the Moon, reusable systems, and the build-up of a cislunar spaceflight infrastructure. Some may not consider this to be “exploration” but the great explorers of history exploited and settled after they found and described.

The attainment of the South Pole one hundred years ago today shifted the meaning of the word exploration and boxed us into an artificial separation of the concepts of discovery and use. That modern connotation is both arbitrary and historically incorrect. Exploration includes exploitation and we can exploit the Moon – our nearest planetary neighbor – to create a permanent space faring capability. The development of cislunar space is exploration in the classic sense – a plunge into the unknown: Can we do this? How hard is it? What benefits – beyond those we can recognize now – might we realize from it? History shows that such undertakings promote new discoveries by opening windows of innovation and generating new streams wealth creation.

Shorty crater is an amazing place on the Moon! From orbital photos, Apollo-era scientists identified this small crater as a place worth visiting. Even though the existing images at the time had limited resolution, analysts could see that Shorty crater was surrounded by a dark (low reflectance) field of ejecta. Since the area seemed to be blanketed by pyroclastic (explosive volcanism) materials, the dark ejecta around Shorty crater led scientists to speculate that perhaps this crater was a volcanic vent, and not an impact scar (see the pre-mission USGS geologic map of Taurus-Littrow). It was yet another reason to send an Apollo lander to the valley of Taurus-Littrow.

Two views of the Taurus-Littrow Valley.
On the left is a composite of three LROC Wide Angle Camera (WAC) color
bands (Red 689 nm, Green 415 nm, Blue 321 nm), and on the right is a
sunrise WAC mosaic. Each image covers the same area and is 40 km wide. View the larger LROC context image HERE [NASA/GSFC/Arizona State University].

On 11 December 1972, Apollo 17 landed in the middle of this fascinating valley. The mission goals included sampling rocks and soil that might reveal the age of the distant Tycho crater forming impact, sampling ancient highland material that might reveal the ages of two mighty basins, return another variety of basalt, collect dark pyroclastic material, and see if Shorty crater was indeed a volcanic vent. Shorty crater is found (white arrow, left WAC mosaic) on a tongue of high reflectance material emanating from South Massif (labeled 'SM' on right right mosaic), about 7 km to the west of the Apollo 17 landing site (yellow arrow).

Apollo 17 astronauts Harrison "Jack" Schmitt and Eugene "Gene" Cernan spent three days performing a reconnaissance exploration of part of Taurus-Littrow Valley. On the second day they drove the Lunar Roving Vehicle (LRV) as far as 8.7 km WSW of the Lunar Module (LM), to the edge of Nansen crater, at the foot of South Massif. On the way back to the LM they headed north across Lee Lincoln scarp (a thrust fault), and on to Shorty crater. It was at the edge of Shorty crater where Schmitt first noticed orange soil underfoot! At the moment it seemed that the crew had indeed discovered oxidized rock, a sure sign of fumarolic volcanic vent.

One frame of the 360° panorama sequence
obtained by Gene Cernan some 40 meters east of the orange glass
sampling site. Harrison Schmitt is seen by the parked LRV. Box
highlights orange soil on the steep wall of the crater, black arrow
points out rock also arrowed on the NAC view above. Apollo 17 Hasselblad
AS17-137-21009 [NASA].

Harrison Schmitt, a life-long geologist, is still very active in the planetary science community and wrote a few thoughts upon seeing the new NAC image of Shorty crater.

"The location of the one-wall trench I dug across the crater rim to get samples of the orange glass and the black partially crystallized glass beneath it. I dug the trench wall so it faced the sun to provide good photographic images. Using the sampling scoop I normally carried, I threw the trench debris so that it all went away from the boulder. Being orange rather than gray, the debris is slightly lighter than the surrounding surface debris (regolith), and is visible as a spray pattern in the image."

"Shorty Crater is about 14 m deep. Based on our investigations at the site and later examination of photographs, the impact that formed it penetrated, in order, regolith on the avalanche deposit, the avalanche deposit, regolith on a basalt flow, a basalt flow overlying and protecting the orange and black glass layers, the orange and black glass layers, regolith on a second basalt flow, and, finally, the upper portion of that second flow. Orange and black glass clods and basalt boulders are spread throughout the ejecta blanket surrounding Shorty." -Harrison H. Schmitt, Lunar Module Pilot and Geologist, Apollo 17

You can see the orange soil that Schmitt sampled in the surface photo shown above, note also the streamer of orange glass extending down the the steep inner wall of the crater (indicated with black box). To help orient yourself in the surface image, imagine yourself standing on the spot marked 'Color Pan' in the NAC image, that is the viewpoint from where Gene captured his 360° panorama series of photographs. If you look closely in the NAC image, you can trace Cernan's tracks from the area of the trench that Schmitt dug, and then back to the rover (two darker parallel lines).

As it turns out the orange soil was not oxidized vent material, but something equally exciting -- titanium-rich pyroclastic glass! When the Shorty impact event occurred, the pyroclastic glass was excavated from about 10 meters below the surface and thrown out onto the rim. Talk about a case of lucky timing! The orange glass was deposited several billion years ago, then shortly after it was deposited, a thin layer of basalt flooded this portion of the valley and formed a protective cap. Then, not too long ago, the orange glass was brought to the surface and the Apollo 17 crew arrived. Eventually the Shorty crater deposits will get churned back into the surrounding landscape by small impacts: Schmitt and Cernan came by at just the right time.

What did we learn from the orange and black soil? These key samples showed that the idea that the valley had witnessed very large fire fountaining eruptions was correct. Imagine lava being erupted so fast that it shot up many hundreds of meters, and splashed over the terrain for many tens of kilometers. Why so high? Because there were large amounts of gases in the magma that rapidly exsolved as it neared the surface. A process similar to what you experience upon shaking a soda can and opening it up -- spray! Scientists were able to find minute remnants of volatiles on the glass beads (both orange and black), including zinc and sulfur. From the extent of the deposit and its composition, it was clear that these materials came from deep sources within the mantle. So by simply walking to the edge of this small, seemingly insignificant, crater the crew were able to sample and bring back incredibly valuable samples of the deep Moon.

That is not the end of the story, the next day Cernan and Schmitt drove north and then east to sample the North massif (NM) and the Sculptured hills (SH). Both destinations were older than the mare, they represented two different ancient crustal samples. From these rocks scientists were able to determine absolute age dates for the formation of an ancient basin. All-in-all Apollo 17 was a smashing success for both science and engineering.